Means for aging vacuum tubes



Feb. 22, 1938. D, UL EY 2,109,225

- MEANS FOR AGING VACUUM TUBES Filed NOV. 28, 1 956 /0 l6 /5 A9 A5 /3 WITNESSES; INVENTOR Dayfon U/rey ATTORN Y Patented Feb. 22, 1938 UNITED sTATEs MEANS FOR AGING VACUUM TUBES Dayton Ulrey, Forest Hills, Pa., assignor to Westinghouse Electric & Manufacturing Company,

East Pittsburgh, Pa., a. corporation of Pennsylvania Application November 28, 1936, Serial No. 113,159

6 Claims.

My invention relates to vacuum tubes, and especially to a method of aging vacuum tubes.

An object of my invention is to provide means for aging vacuum tubes so that they will not spark over at voltages that they would otherwise withstand.

Other objects and advantages of my invention will be apparent from the accompanying description and drawing, in which the figure is a diagrammatic circuit showing a preferred embodiment of my invention.

In vacuum tubes using very high voltages, considerable trouble is caused by fiashovers that interrupt the performance of the tube. The tubes in which the trouble occurred were of the copper exterior anode and interior directly heated, cathode that were normally designed to withstand very high voltages. It was found that these tubes with the cathode unheated would break down at voltages around 20,000 to 30,000, although designed for a much higher peak voltage. I believe that one of the causes of these fiashovers is probably caused. by some occluded gas that had been released after the tube had been sealed off.

I have discovered that the tube can be aged against fiashovers at these voltages by providing instantaneous or temporary discharges of hundreds of amperes. I believe a discharge at a high amperage across the condenser probably cleans up this residual occluded gas that apparently causes the difliculty with these high powered tubes.

According to my invention, I have provided a means for discharging hundreds of amperes through a tube and then raise the voltage of this high instantaneous current still higher until another flashover occurs, and then I repeat the process until the tube can withstand the desired voltage without fiashover.

In the drawing, represents the tube to be aged, having the usual cathode II and anode l2 which, of course, in these'high voltage tubes is a copper exterior water cooled anode. The tube may also contain one or more auxiliary electrodes such as the grid l3. For the purpose of my invention, I connect the grid and cathode together as shown at M. Across the anode and cathodegrid is connected the high voltage condenser I5 with its plates l6 and II. A high voltage voltmeter IB may also be connected across the electrodes. Power is supplied from 7 any suitable source l9 which may, of course, include the transformer and a rectifier 20 to provide the uni-directional current if alternating current is used. A

high resistance 2| is also inserted in the charging circuit.

In operation of the device, the power source 19 operating through the rectifier 20 charges the plates l6 and I! to a high voltage. The voltage is increased until the tube flashover, thus discharging the condenser. The condenser then charges again and the process is repeated indefinitely. The Voltage on the condenser increases as the tube improves and incidentally the number of the flashovers of the tube during a given period represent a measure of the quality of the tube as regards withstanding voltage. By means of my invention, tubes which would break down at voltages as low as 20,000 to 30,000 volts can now be aged up to withstand as high as 50,000 volts and higher. These tubes are used extensively in broadcasting service, and my invention provides means for minimizing the interruption to the broadcasting service heretofore caused by tubes fiashing over at less than their peak rating of voltage.

The voltage to which the condenser is to be charged will determine the rating of the transformer IS. The rating of the condenser l5 depends on how rapidly it is desired to haveit charged. In general, I prefer to use from onetenth to one-half microfarad capacity condenser.

While I have disclosed a preferred embodiment of my invention, yet modifications thereof are possible within the scope of my invention. I accordingly, therefore, desire only such limitations on the following claims as is necessitated by the prior art.

I claim as my invention:

1. The method of aging vacuum tubes which comprises establishing a vacuum therein and causing a series of fiashovers between electrodes in the vacuum without heating current applied to the cathode.

2. The method of aging vacuum tubes which comprises causing a series of flashovers between electrodes without heating current applied to the cathode and increasing the voltage of the succeeding flashovers.

3. The method of aging vacuum tubes which comprises connecting a condenser to the electrodes thereof while the heating current for the cathode is disconnected, charging the condenser, permitting the condenser to discharge across the electrodes and recharging the condenser and per mitting it to discharge across the electrodes.

e. The method of aging vacuum tubes which comprises connecting a condenser to the electrodes thereof while the heating current for the ing the condenser and discharging the condenser through the tube.

6. The method of aging vacuum tubes which 7 comprises connecting a condenser across the electrodes without connecting the heating current to the cathode, charging the condenser to the order of tens of thousands of volts, discharging the condenser through the tube and recharging the condenser to a higher voltage and discharging the condenser through the tube.

" DAYTON ULREY. 

